Input device

ABSTRACT

The image sensor  15  of the information processing apparatus  1  can capture the retroreflective sheet  17  subjected to infrared light emitted from the infrared emitting diodes  11  since the retroreflective sheet  17  is exposed when the open-close portion  19  is opened. Therefore, it is possible to detect the input device  3 . On the other hand, when the open-close portion  19  is closed, the image sensor  15  can not capture the retroreflective sheet  17  since the reflective sheet  17  is not exposed. Therefore, the input device is not detected.

This Application is a Continuation of U.S. application Ser. No.11/573,724 (PCT/JP2005/015600) filed 23 Aug. 2005 for INPUT DEVICE, nowU.S. Pat. No. 7,719,741, the contents of which is hereby incorporated byreference.

TECHNICAL FIELD

The present invention is related to an input device comprising areflective portion as an object which is captured by a stroboscope, andthe related techniques thereof.

BACKGROUND ART

A golf game system of the present applicant is described in Jpn.unexamined patent publication No. 2004-85524. The golf game systemincludes a game apparatus and a golf club type input device, and animaging unit including an image sensor and infrared emitting diodes isprovided within a housing of the game apparatus. The infrared emittingdiodes intermittently emit infrared light to a prescribed area above theimaging unit. Therefore, the image sensor intermittently picks up animage of a reflective portion attached to the golf club type inputdevice which moves within the prescribed area. The speed of the golfclub type input device which is an input to the game apparatus iscalculated by processing images of the reflective portion captured bythe stroboscope. In this way, input is given to a computer or a gameapparatus in real time by means of the stroboscope.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide an input devicewhich comprises a reflective portion as an object captured by astroboscope, can give input to an information processing apparatus inreal time, and can be easily controlled to input or un-input, and therelated techniques thereof.

In accordance with a first embodiment of the present invention, an inputdevice as an object being captured by strobing, is operable to input toan information processing apparatus which performs processing inaccordance with a program, and comprises: a retroreflective member; aunit where said retroreflective member is attached; and a supportingbody where said unit is attached rotatably, and wherein saidretroreflective member is attached on a predetermined face of said unitand a direction which the predetermined face faces is different inresponse to rotating of said unit.

In accordance with this configuration, an operator can easily controlinput/un-input to the information processing apparatus since it ispossible to control the direction which the retroreflective member facesonly by rotating the unit where the retroreflective member is attached.

In accordance with a second embodiment of the present invention, aninput device as an object being captured by strobing, is operable toinput to an information processing apparatus which performs processingin accordance with a program, and comprises: a retroreflective member; aunit where said retroreflective member is attached; and a supportingbody where said unit is attached so as to be opened and closed, andwherein said retroreflective member is attached to said unit in a mannerthat said retroreflective member is located between said unit and saidsupporting body when said unit is either closed or opened.

In accordance with this configuration, an operator can easily controlinput/un-input to the information processing apparatus since it ispossible to control exposure of the retroreflective member only byopening/closing the unit where the retroreflective member is attached.

In accordance with a third embodiment of the present invention, an inputdevice as an object being captured by strobing, is operable to input toan information processing apparatus which performs processing inaccordance with a program, and comprises: a retroreflective member; ashutter which exposes said retroreflective member when said shutter isopened and does not expose said retroreflective member when said shutteris closed.

In accordance with this configuration, an operator can easily controlinput/un-input to the information processing apparatus since it ispossible to control exposure of the retroreflective member only byopening/closing the shutter.

BRIEF DESCRIPTION OF DRAWINGS

The aforementioned and other features and objects of the presentinvention and the manner of attaining them will become more apparent andthe invention itself will be best understood by reference to thefollowing description of a preferred embodiment taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a view showing the overall configuration of an informationprocessing system in accordance with the embodiment of the presentinvention.

FIG. 2A is a perspective view showing the input device 3 of FIG. 1 whenan open-close portion 19 is closed.

FIG. 2B is a perspective view showing the input device 3 of FIG. 1 whenthe open-close portion 19 is opened.

FIG. 3A is a front view showing the input device 3 of FIG. 1 when theopen-close portion 19 is closed.

FIG. 3B is a front view showing the input device 3 of FIG. 1 when theopen-close portion 19 is opened.

FIG. 4A is a plan view showing the input device 3 of FIG. 1 when theopen-close portion 19 is closed.

FIG. 4B is a plan view showing the input device 3 of FIG. 1 when theopen-close portion 19 is opened.

FIG. 5 is a side view showing a supporting portion 21 of the inputdevice 3 of FIG. 1.

FIG. 6 is a side view showing the open-close portion 19 of the inputdevice of FIG. 1.

FIG. 7 is a view showing the input device 3 of FIG. 1 being held by anoperator with a right hand.

FIG. 8 is a view showing the electrical construction of the informationprocessing apparatus 1 of FIG. 1.

FIG. 9 is a flowchart showing the entire operation of the informationprocessing apparatus 1 of FIG. 1.

FIG. 10 is a flowchart showing the process flow of imaging process instep S2 of FIG. 9.

FIG. 11 is a flowchart showing the process flow of target areaextracting process in step S3 of FIG. 9.

FIG. 12 is a flowchart showing the process flow of the target pointextracting process in step S4 of FIG. 9.

FIG. 13A is a perspective view showing other example of the input device3 when its shutter is closed.

FIG. 13B is a perspective view showing the input device 3 of FIG. 13Awhen its shutter is opened.

FIG. 13C is a front view showing the input device 3 of FIG. 13A when itsshutter is opened.

BEST MODE FOR CARRYING OUT THE INVENTION

In what follows, an embodiment of the present invention will beexplained in conjunction with the accompanying drawings. Meanwhile, likereferences indicate the same or functionally similar elements throughoutthe respective drawings, and therefore redundant explanation is notrepeated.

FIG. 1 is a view showing the overall configuration of an informationprocessing system in accordance with the embodiment of the presentinvention. As illustrated in FIG. 1, this information processing systemincludes an information processing apparatus 1, an input device 3 and atelevision monitor 5.

The information processing apparatus 1 is connected to the televisionmonitor 5 with an AV cable 7. A DC power voltage is supplied to theinformation processing apparatus 1 through an AC adapter or a battery(not shown). A power switch 13 is provided on the upper surface of theinformation processing apparatus 1.

The information processing apparatus 1 is also provided with an infraredfilter 9 which transmits only infrared light, and four infrared emittingdiodes 11 which emit infrared light are positioned around the infraredfilter 9 and exposed. An image sensor 15 to be explained later ispositioned behind the infrared filter 9.

The four infrared emitting diodes 11 intermittently emit infrared light.Then, the infrared light emitted from the infrared emitting diodes 11 isreflected by the retroreflective sheet 17 (to be explained later)attached on the input device 3, and input to the image sensor 15 locatedbehind the infrared filter 9. In this way, the input device 3 iscaptured by the image sensor 15. Even though infrared light is emittedintermittently, the image sensor 15 also performs imaging process duringnon-lighted period of infrared light. The information processingapparatus 1 obtains a differential signal between image signals of theinput device 3 moved by an operator with and without lighted, andcalculates position of the input device 3 (i.e., the retroreflectivesheet 17) on the basis of the differential signal.

FIG. 2A is a perspective view showing the input device 3 of FIG. 1 whenan open-close portion 19 is closed, and FIG. 2B is a perspective viewshowing the input device 3 of FIG. 1 when the open-close portion 19 isopened. FIG. 3A is a front view showing the input device 3 of FIG. 1when the open-close portion 19 is closed, and FIG. 3B is a front viewshowing the input device 3 of FIG. 1 when the open-close portion 19 isopened. FIG. 4A is a plan view showing the input device 3 of FIG. 1 whenthe open-close portion 19 is closed, and FIG. 4B is a plan view showingthe input device 3 of FIG. 1 when the open-close portion 19 is opened.FIG. 5 is a side view showing a supporting portion 21 of the inputdevice 3 of FIG. 1. FIG. 6 is a side view showing the open-close portion19 of the input device of FIG. 1. FIG. 7 is a view showing the inputdevice 3 of FIG. 1 being held by an operator with a right hand.

As illustrated in these figures, the input device 3 includes theopen-close portion 19 and the supporting portion 21. The upper half ofthe supporting portion 21 is referred as a head, and the lower half isreferred as a grip. The open-close portion 19 is attached to the head ofthe supporting portion 21 so as to be freely opened and closed.

As illustrated in FIG. 6, a semicircular retroreflective sheet 17 isattached on one side of the open-close portion 19. Namely, theopen-close portion 19 is a unit where the retroreflective sheet 17 isattached. Cylindrical salient portions 23 are formed on the same axis asa rotary shaft on the upper surface and the lower surface of theopen-close portion 19. In addition, a lever portion is formed in amanner to project toward the opposite side of the retroreflective sheet17 from near the salient portion 23 on the upper surface of theopen-close portion 19. Incidentally, the lever portion 25 is referred asa tale of the open-close portion 19, and the opposite side of the leverportion 25 across the rotary shaft (i.e., a substantially semicircularlycylindrical portion where the retroreflective sheet 17 is attached) issometimes referred as a head of the open-close portion 19.

In addition, as illustrated in FIG. 5, a substantially semicircularlycylindrical concave portion 27 is formed on one side of the head of thesupporting portion 21 so that the head of the open-close portion 19 canfit in. Axial holes (not shown) to insert the salient portions 23 areformed on both ends (indicated by arrows “a”) of the inner wall of theconcave portion 27.

Then, the salient portions 23 of the open-close portion 19 are insertedto the respective axial holes formed on the both end of the inner wallof the concave portions 27, and the input device 3 is finally completed.In this way, the open-close portion 19 is attached to the supportingportion 21 so as to be freely rotated by using the salient portions 23as the rotary shaft.

When an operator, for example, holds the input device 3 with a righthand and rotates the lever portion 25 of the open-close portion 19 whichis closed (refer to FIGS. 2A, 3A and 4A) with a right thumb, theopen-close portion 19 opens (refer to FIGS. 7, 2B, 3B and 4B). Also,when an operator, for example, holds the input device 3 with a righthand and rotates, in the reverse direction, the lever portion 25 of theopen-close portion 19 which is opened with a right thumb, the open-closeportion 19 closes in a manner that fits into the concave portion 27.

When the operator turns the retroreflective sheet 17 of the open-closeportion 19 which is opened toward the infrared filter 9 (i.e., the imagesensor 15) of the information processing apparatus 1, the image sensor15 picks up an image of the retroreflective sheet 17 subjected to theinfrared light emitted from the infrared emitting diodes 11 so that theinformation processing apparatus 1 can detect the input device. On theother hand, even if the operator turns the input device 3 with theopen-close portion 19 being closed toward the infrared filter 9 of theinformation processing apparatus 1, the retroreflective sheet 17 is notcaptured since the reflective sheet 17 is hidden in the concave portion27 of the supporting portion 21 so it can not be subjected to theinfrared light. Therefore, the information processing apparatus 1determines the input device does not exist.

As has been discussed above, it is possible to control easily to inputor un-input to the information processing apparatus 1 by controllingopen/close operation of the input device 3. Incidentally, theinformation processing apparatus 1 determines that there is input whenthe input device 3 is detected; the information processing apparatus 1determines that there is not an input when the input device 3 is notdetected; and vice versa.

FIG. 8 is a view showing the electrical construction of the informationprocessing apparatus 1 of FIG. 1. As illustrated in FIG. 8, theinformation processing apparatus 1 includes the image sensor 15, theinfrared emitting diodes 11, a high speed processor 31, a ROM (read onlymemory) 33, and a bus 35.

The input device 3 with the open-close portion 19 opened is irradiatedby infrared light emitted from the infrared emitting diodes 11 andreflects the infrared light with the retroreflective sheet 17. Theinfrared light reflected by the retroreflective sheet 17 is captured bythe image sensor 15. Therefore, an image signal of the retroreflectivesheet 17 is output from the image sensor 15. The analog image signalfrom the image sensor 15 is converted to a digital data by an A/Dconverter (not shown) of the high speed processor 31. Incidentally, thehigh speed processor 31 makes the infrared emitting diodes 11 flashintermittently to perform strobing.

The high speed processor 31, even though not shown in figures, alsoincludes various function blocks such as a CPU (central processingunit), a graphics processor, a sound processor and a DMA controller; theA/D converter which is used when an analog signal is input; and aninput/output control circuit which receives input signals such as a keyoperation signal and an infrared signal and transmits output signals toexternal devices. Input signals are transmitted to the CPU. The CPUperforms necessary calculations in response to the input signals andgives the results to the graphics processor and the sound processor.Therefore, the graphics processor and the sound processor perform imageprocessing and sound processing in accordance with the results of thecalculation.

In addition, the high speed processor 31 includes an internal memory(not shown) which, for example, consists of a RAM (random accessmemory). The internal memory is utilized as a working area, a counterarea, a temporary area and/or a flag area.

The high speed processor 31 can access the ROM 33 through the bus 35.Therefore, the high speed processor 31 can execute a program stored inthe ROM 33, and read and process data stored in the ROM 33. A program,image data, sound data and so on are stored in the ROM 33 in advance.

The high speed processor 31 processes digital image signals input fromthe image sensor 15 via the A/D converter, and detects whether or notthere is input from the input device 3 and position of the input device3. Then, the high speed processor 31 performs calculation, graphicprocessing, and sound processing, and then outputs a video signal and anaudio signal. The video signal and the audio signal are given to thetelevision monitor 5 via the AV cable 7. Consequently, an image isdisplayed on the television monitor 5 and a sound is output from aspeaker (not shown).

FIG. 9 is a flowchart showing the entire operation of the informationprocessing apparatus 1 of FIG. 1. As illustrated in FIG. 9, the highspeed processor 31 performs the initial setting of the system in stepS1. In step S2, the high speed processor 31 activates the infraredemitting diodes 11 and performs imaging processing of the input device3.

In step S3, the high speed processor 31 performs extracting process of atarget area of the input device 3. In step S4, the high speed processor31 extracts a target point of the input device 3. In step S5, the highspeed processor 31 performs information processing using the results ofthe processing of step S3 and S4.

In step S6, the high speed processor 31 judges whether or not a variable“M” is smaller than a predetermined value “K”. If the variable “M” isequal to or larger than the predetermined value “K”, the high speedprocessor 31 proceeds to step S7, assigns “0” to the variable “M”, andthen proceeds to step S8. On the other hand, if the variable “M” issmaller than the predetermined value “K”, the high speed processor 31proceeds from step S6 to step S8.

If it is “Yes” in step S8, i.e., the high speed processor 31 waits forthe video system synchronous interrupt (i.e., as long as the videosystem synchronous interrupt is not issued), the high speed processor 31returns to the same step S8. On the other hand, if it is “No” in stepS8, i.e., the high speed processor 31 gets out of the state of waitingfor the video system synchronous interrupt (i.e., if the high speedprocessor 31 is given the video system synchronous interrupt), the highspeed processor 31 proceeds to step S9. In step S9, the high speedprocessor 31 performs update processing of the screen image displayed onthe television monitor 5 and then proceeds to step S2.

The sound processing in step S10 is performed when there is a soundinterrupt, and consequently music and sound effects are output.

FIG. 10 is a flowchart showing the process flow of imaging process instep S2 of FIG. 9. As illustrated in FIG. 10, the high speed processor31 makes the infrared emitting diodes 11 flash to perform strobing instep S20. In step S21, the high speed processor 31 obtains, from theimage sensor 15, image data with lighted and stores it in the internalmemory.

In this embodiment, the CMOS image sensor which consists of 32 pixels×32pixels is used as an example of the image sensor 43. The horizontaldirection is a direction of X axis and the vertical direction is adirection of Y axis. Therefore, 32 pixels×32 pixels of pixel data(luminance data for each pixel) is output as an image data from theimage sensor 15. This pixel data is converted to digital data by the A/Dconverter, and stored in an array P1[X][Y] in the internal memory.

In step S22, the high speed processor 31 makes the infrared diodes 11un-flash. In step S23, the high speed processor 31 obtains, from theimage sensor 15, image data without lighted (32 pixels×32 pixels ofpixel data (luminance data for each pixel)), and stores it in theinternal memory. In this case, the image data without lighted is storedin an array P2[X][Y] in the internal memory.

Incidentally, since 32×32 pixel image sensor 15 is used in thisembodiment, X=0 to 31, Y=0 to 31, and a corner on upper left is definedas an origin.

FIG. 11 is a flowchart showing the process flow of target areaextracting process in step S3 of FIG. 9. As illustrated in FIG. 11, thehigh speed processor 31 assigns “0” to a counter “C” in step S30. Instep S31, the high speed processor 31 calculates difference betweenpixel data P1[X][Y] with light emitted from the infrared emitting diodes11 and pixel data P2[X][Y] without light emitted from the infraredemitting diodes 11. The difference data is assigned to an arrayDif[X][Y].

In this way, it is possible to eliminate light (or noise) except returnlight from the retroreflective sheet 17 as much as possible by obtainingthe difference data so that it is possible to detect the retroreflectivesheet 17 with high accuracy.

In step S32, the high speed processor 31 compares an element of thearray Dif[X][Y] with a predetermined threshold “Th”. In step S33, if theelement of the array Dif[X][Y] is larger than the predeterminedthreshold “Th”, the high speed processor 31 proceeds to step S34,otherwise proceeds to step S35.

In step S34, the high speed processor 31 increments the count value “C”by one to count the number of the difference data (the elements of thearray Dif[X][Y]) exceeding the predetermined threshold value “Th”. Thehigh speed processor 31 repeats the process from step S32 to S34 untilthe high speed processor 31 finishes comparing all elements of the arrayDif[X][Y] with the predetermined threshold value “Th” (in step S35). Thefinal count value “C” is the size of the target area of the input device3.

FIG. 12 is a flowchart showing the process flow of the target pointextracting process in step S4 of FIG. 9. As illustrated in FIG. 12, thehigh speed processor 31 determines whether or not the count value “C”(refer to step S34 of FIG. 11) is “0” in step S40. If the count value“C” is “0”, the high speed processor 31 proceeds to step S47, otherwiseproceeds to step S41.

Incidentally, if the count value “C” is “0”, it means theretroreflective sheet 17 of the input device 3 is not detected, i.e.,the open-close portion 19 of the input device 3 is closed (for example,there is no input). If the count value “C” is not “0”, it means theretroreflective sheet 17 of the input device 3 is detected, i.e., theopen-close portion 19 of the input device 3 is opened (for example,there is input).

In step S47, the high speed processor 31 turns off a detection flagwhich indicates whether or not the input device 3 is detected. On theother hand, the high speed processor 31 turns the detection flag on instep S41.

In step S42, the high speed processor 31 scans all elements of the arrayDif[X][Y] and detects a maximum value. The X coordinate and the Ycoordinate of the maximum value is defined as the coordinate (Xc, Yc) ofthe target point. In step S43, the high speed processor 31 incrementsthe variable “M” by one.

In step S44, the high speed processor 31 assigns the coordinates “Xc”and “Yc” to an array PX[M] and PY[M]. In step S45, the high speedprocessor 31 calculates a moving average (AX, AY) of the target point(Xc, Yc) of the input device 3. In step S46, the high speed processor 31converts the average coordinate (AX, AY) of the target point on theimage sensor 15 into a coordinate (xc, yc) on the television monitor 5.

Returning to FIG. 9, the high speed processor 31 performs variousprocessing on the basis of the coordinate (xc, yc) of the target pointand in response to input/un-input from the input device 3 in referenceto the detection flag.

FIG. 13A is a perspective view showing other example of the input device3 when its shutter is closed; FIG. 13B is a perspective view showing theinput device 3 of FIG. 13A when its shutter is opened; and FIG. 13C is afront view showing the input device 3 of FIG. 13A when its shutter isopened.

As illustrated in these drawings, the input device 3 includes a headportion 50 and a body portion 51. The head portion 50 is attached on thefront side of upper part of the body portion 51. Incidentally, the lowerpart of the body portion 51 is a grip where an operator holds.

As illustrated in FIG. 13C, a rectangular aperture 56 is formed on thehead portion 50, and the retroreflective sheet 17 is attached on thebottom part of the aperture 56.

When a button 54 of the body portion 51 is not pressed, a plurality ofslats 52 are closed. Therefore the retroreflective sheet 17 is notexposed since the aperture 56 is covered with the slats 52 (refer toFIG. 13A). On the other hand, when the button 54 of the body portion 51is pressed, the slats are opened (refer to FIGS. 13B and 13C).Therefore, the retroreflective sheet 17 is exposed from the aperture 56.

When an operator turns the retroreflective sheet 17 with the slats 52opened toward the infrared filter 9 (i.e., the image sensor 15) of theinformation processing apparatus 1, the retroreflective sheet 17subjected to the infrared light from the infrared emitting diodes 11 iscaptured by the image sensor 15 so that the information processingapparatus 1 can detect the input device 3. On the other hand, when anoperator turns the input device 3 with the slats 52 closed toward theinfrared filter 9 of the information processing apparatus 1, theretroreflective sheet 17 is not captured since the retroreflective sheet17 is covered with the slats 52 and not exposed to infrared light.Therefore, the information processing apparatus 1 determines the inputdevice does not exist.

As has been discussed above, it is possible to control exposure of theretroreflective sheet 17 by opening/closing the shutter which is made ofa plurality of the slats 52. Therefore, to control input/un-input to theinformation processing apparatus 1, the operator simply opens and closesthe slats 52. Incidentally, if the input device 3 is detected, it isconsidered to be there is input in the same way as the input device 3 ofFIG. 1, and if the input device 3 is not detected, it is considered tobe there is not input from the input device 3, and vice versa.

Incidentally, the present invention is not limited to the aboveembodiment, and a variety of variations and modifications may beeffected without departing from the spirit and scope thereof, asdescribed in the following exemplary modifications.

(1) The open-close portion 19 is rotated around the vertical shaft inFIGS. 2A and 2B. However, for example, it can be rotated around ahorizontal shaft, and also it is possible to decide the direction of therotation arbitrarily. In addition, the contours of the open-closeportion 19 and the supporting portion 21 are not limited thereto, andthe shape of the retroreflective sheet 17 can be made arbitrarily. Inabove description, the open-close portion 19 is opened/closed by hand.However, the open-close portion 19 can be opened/closed for example, bypressing a button.

(2) In FIG. 13A to 13C, the exposure of the retroreflective sheet 17 iscontrolled by the shutter which is made of the plurality of slats 52.However, it is not limited thereto, and the exposure of theretroreflective sheet 17 can be controlled by one plate which covers theaperture 56. In this case, the shutter can be opened/closed by slidingthe plate vertically or horizontally, rotating on one point on theplate, or rotating around one side line of the plate as a shaft. Thecontours of the aperture 56 and the retroreflective sheet 17 are notlimited to rectangular. They can be made any arbitrary shape. Needlessto say, the contours of the head portion 50 and the body portion 51 arenot limited thereto, and they can be made any arbitrary shape. In aboveexplanation, the retroreflective sheet 17 is attached on the bottom ofthe aperture 56. However, instead of forming the aperture 56 on thesurface of the head portion 50, it is possible to make the surface ofthe head portion 50 flat and attach the retroreflective sheet 17 on thesurface.

(3) For the method of controlling exposure of the retroreflective sheet17, a lens shutter mechanism used in a compact camera or a focal planeshutter mechanism used in a single-lens reflex camera can be employed.Also, an aperture mechanism of camera using aperture blades can beemployed. Furthermore, a liquid-crystal shutter can be used as themethod of controlling exposure of the retroreflective sheet 17.

(4) In above explanation, if a difference data corresponding to at leastone pixel is larger than the threshold value “Th”, the high speedprocessor 31 determines that the input device 3 is detected (refer tostep S41 of FIG. 12). However, in addition to the condition explainedabove, it is possible to use a condition which the count value “C”(corresponding to the area of the target area) is larger than theprescribed value as a condition for detecting the input device 3.

(5) In the input device 3 of FIG. 1, input/un-input to the informationprocessing apparatus 1 is controlled by opening/closing operation of theopen-close portion 19. In above explanation, the term “open-close” isused. However, it is possible to turn the reflective sheet 17 toward theimage sensor 15 or toward the opposite direction of the image sensor 15to control input/un-input to the information processing apparatus 1 byrotating the open-close portion 19 (i.e., the member where thereflective sheet 17 is attached) around a shaft.

The foregoing description of the embodiments has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form described, andobviously many modifications and variations are possible in light of theabove teaching. The embodiment was chosen in order to explain mostclearly the principles of the invention and its practical applicationthereby to enable others in the art to utilize most effectively theinvention in various embodiments and with various modifications as aresuited to the particular use contemplated.

1. An input device for operating with a system having a detector thatconditionally detects the input device, the input device comprising: acontact portion configured to enable support of the input device with ahand; and a retroreflective member configured to move from a firstposition to a second position, relative to the contact portion,responsive to the hand while the hand is supporting the input device viathe contact portion, to disable the detector from detecting the inputdevice, and configured to move from the second position to the firstposition responsive to the hand while the hand is supporting the inputdevice via the contact portion, to enable the detector to detect theinput device.
 2. The input device of claim 1 wherein the retroreflectivemember includes a retroreflective sheet.
 3. A system comprising: aninput device including a contact portion configured to enable support ofthe input device with a hand, and a retroreflective member configured tomove from a first position to a second position, relative to the contactportion, responsive to the hand while the hand is supporting the inputdevice via the contact portion, to disable the detector from detectingthe input device, and configured to move from the second position to thefirst position responsive to the hand while the hand is supporting theinput device via the contact portion, to enable the detector to detectthe input device; and a detector that detects the input device dependingon whether the retroreflective member is in the first position.
 4. Thesystem of claim 3 wherein the retroreflective member includes aretroreflective sheet.
 5. The system of claim 3 wherein the detector isconfigured to determine a first coordinate, the first coordinatecorresponding to a position of the input device on a first axis, anddetermine a second coordinate, the second coordinate corresponding to aposition of the input device on a second axis, the second axis beingperpendicular to the first axis.
 6. The system of claim 3 wherein thedetector is configured to determine a first coordinate, the firstcoordinate corresponding to a position on a first axis, and determine asecond coordinate, the second coordinate corresponding to a position ona second axis, the second axis being perpendicular to the first axis. 7.A method for operating with input device including a contact portionconfigured to enable support of the input device with a hand, and aretroreflective member, the method comprising: moving theretroreflective member from a first position, relative to the contactportion, to a second position responsive to the hand while the hand issupporting the input device via the contact portion; moving theretroreflective member from the second position to the first positionresponsive to the hand while the hand is supporting the input device viathe contact portion; and detecting the input device depending on whetherthe retroreflective member is in the first position.
 8. The method ofclaim 7 wherein the retroreflective member includes a retroreflectivesheet.
 9. The method of claim 7 further including determining a firstcoordinate, the first coordinate corresponding to a position of theinput device on a first axis, and determines a second coordinate, thesecond coordinate corresponding to a position of the input device on asecond axis, the second axis being perpendicular to the first axis. 10.A system comprising: an input device including a first portion, and aretroreflective member configured to move between a first positionrelative to the first portion and a second position relative to thefirst portion, responsive to a hand; and a detector that detects theinput device depending on whether the retroreflective member is in thefirst position, determines a first coordinate, the first coordinatecorresponding to a position on a first axis, and determines a secondcoordinate, the second coordinate corresponding to a position on asecond axis, the second axis being perpendicular to the first axis. 11.The system of claim 10 further including a signal generator thatgenerates a video signal in accordance with the first and secondcoordinates, and supplies the video signal to a display device.